Vehicles such as automobiles generally are provided with seat belt devices for restraining an occupant in a seat that includes a seat portion on which the occupant sits and a backrest portion positioned back of the occupant. Such a seat belt device includes a webbing for restraining the occupant, a retractor for retracting the webbing, a guide anchor that is disposed on a vehicle body side and guides the webbing, a belt anchor for fixing the webbing to the vehicle body side, a buckle disposed on a side surface of the seat, and a tongue disposed in the webbing. The tongue is fitted into the buckle to restrain the occupant in the seat with the webbing. In such the seat belt device, a first end of the webbing is fixed to the belt anchor, and a second end of the webbing is inserted into the guide anchor to be connected to the retractor.
Such a retractor includes an emergency locking retractor (ELR), which has an emergency lock mechanism that locks a withdrawal of a webbing in an emergency such as a vehicle collision, and an automatic locking retractor (ALR), which has an automatic lock mechanism that only retracts a webbing to lock a withdrawal of a webbing in mounting a child seat or the like. As a retractor having these lock mechanisms, for example, an ELR having an ALR is mainly used as described in Japanese Unexamined Utility Model Application Publication No. H05-62360.
An automatic lock mechanism described in Japanese Unexamined Utility Model Application Publication No. H05-62360 includes a cam member that is rotated by a shaft of a spool for winding a webbing via a speed reduction mechanism, a pawl control arm that is turned in contact with a switching projection or a lock stopper that are formed on an outer circumference of the cam member, a pawl that is turnably disposed interlocking with the pawl control arm, and a ratchet wheel that is fixed to the shaft of the spool.
In such an automatic lock mechanism, in normal use, the pawl is held in a state being separated from the ratchet wheel (off-state). When all the webbing is withdrawn, the pawl control arm is turned in contact with the switching projection, and accordingly, the pawl is also turned to be switched to a state being locked to the ratchet wheel (on-state). Thereafter, the withdrawal of the webbing is locked until the pawl control arm is brought into contact with a lock stopper. Then, when a certain amount of the webbing is retracted, the pawl control arm is turned in contact with the lock stopper, and accordingly, the pawl is also turned to be switched to a state being separated from the ratchet wheel (off-state).